The aim of Program 2-Physiological Studies in Experimental Spinal Cord Injury will be to investigate the hypothesis that the evolving hemorrhagic necrosis following experimental primary traumatic injury has a secondary dynamic injury component which has significance in the resulting neurological impairment. Physiological studies of metabolism, perfusion, SCBF, (spinal cord blood flow) and SEP (somatosensory evoked potential) will be performed in chronic and acute animal experiments. Standardization and validation of the animal model will be performed in the first year of study in order to determine an optimal trauma dose for investigating the primary and secondary injuries and for later evaluation of therapeutic modalities. Metabolism as determined by 2-deoxy-2-glucose autoradiographic studies, perfusion by thioflavine injection, and SCBF determinations by direct hydrogen electrode technique will be performed acutely in order to substantiate the concept of progressive secondary injury of ischemia and/or metabolism occurring in the white matter following the initial primary injury. The variation of physiological variables (BP and pCO2) and their effects on the above determinations will result in a proposal of physiological and pharmacological therapeutic modalities to be instituted in the final year of study. Program 2 will also provide the basic foundation for the other programs of Fundamental Studies in Spinal Cord Injury.